The first part is about installing a very basic gentoo system in a chrooted partition; in the second part we will use portage to install entropy and equo. Finally we will use equo to install a full sabayon system in the third and last part.

Hostname

Mount points

Part 2: Sabayon overlay setup and installation of entropy+equo

Layman

layman is a gentoo tool to manage portage overlays. We will use it to get our hands on the sabayon overlay.
Update: entropy and equo are in regular portage, so you can skip this step.

# emerge --sync # make sure portage is fully up to date... or not. Up to you. portage snapshots are done daily, i see no need to sync.
# USE="git" emerge -avt layman # now equo is in regular portage!
# layman -a sabayon # see above

Entropy and Equo

emerge -avt equo --autounmask-write
etc-update
emerge -avt equo

Now we have entropy and equo installed. To make use of it, we should first generate the entropy database (only the very first time!):

equo rescue generate

Yes, you are sure about this. You should answer yes three times to make it happy.